From dc610f9ce3e3526e4c9e52337d33b2caec632daf Mon Sep 17 00:00:00 2001
From: Acts1631 <acts1631kjv@proton.me>
Date: Thu, 27 Aug 2026 12:52:49 -0400
Subject: [PATCH] db/update: limit archive entry path length

Archive entries can exceed filesystem path limits. Deep paths make
UpdateArchiveTree() allocate a virtual Directory for each component,
allowing a small ZIP file to consume hundreds of megabytes during a
database update.

Ignore paths that cannot fit within MPD_PATH_MAX.
---
 src/db/update/Archive.cxx | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/db/update/Archive.cxx b/src/db/update/Archive.cxx
index 2f14f6071b..f789ae8463 100644
--- a/src/db/update/Archive.cxx
+++ b/src/db/update/Archive.cxx
@@ -10,6 +10,7 @@
 #include "protocol/Verify.hxx"
 #include "lib/fmt/PathFormatter.hxx"
 #include "fs/AllocatedPath.hxx"
+#include "fs/Limits.hxx"
 #include "storage/FileInfo.hxx"
 #include "archive/ArchiveList.hxx"
 #include "archive/ArchivePlugin.hxx"
@@ -40,6 +41,9 @@ void
 UpdateWalk::UpdateArchiveTree(ArchiveFile &archive, Directory &directory,
 			      std::string_view name) noexcept
 {
+	if (name.size() >= MPD_PATH_MAX)
+		return;
+
 	const auto [child_name, rest] = Split(name, '/');
 	if (rest.data() != nullptr) {
 		if (!VerifyRelativePathUTF8(child_name))